In recent years, with finer semiconductor devices, methods for forming patterns having a dimension less than the exposure resolution limit of lithography have been desired. As one of such methods, there has been known a method for forming side wall patterns on the side surfaces of a dummy pattern (core) and using the side wall patterns as a mask to perform the etching of a film to be processed. The dummy pattern between the side wall patterns is removed by a wet process. There has been the problem that the side wall patterns are fallen due to the surface tension of a chemical solution (or pure water) entering between the side wall patterns at the time of a drying process after the wet process. There has been known a method for preventing the falling of patterns by substituting the pure water on a wafer with IPA (isopropyl alcohol) having smaller surface tension than the pure water to dry the substrate. However, even with the IPA, it is difficult to prevent the falling of the fine patterns formed by the above method.
In addition, typically, a plurality of patterns are present on one chip, and resist patterning and an etching process, such as wet etching and dry etching, are performed to produce different types of patterns. After pattern etching is performed in a region being not covered by a resist, an ashing and/or SPM (Sulfuric Acid Hydrogen Peroxide Mixture) process is performed for releasing the resist. However, such method has the problem that the number of steps is large, resulting in increased manufacturing cost. In addition, when the resist is released by the wet process to dry the substrate, the fine patterns can be fallen.